Supervisory system



June 6, 1933. w. BRUcKL ET AL SUPERVISORY SYSTEM Filed June 9, 1930 4 Sheets-Sheet l h 9 E m ICF u o wvw t 3. t T] A ar: r W? .6 ed h M m T b H i i June 6, 1933. w. BRUCKEL ET AL SUPERVISORY SYSTEM Filed June 9, 1930 4 Sheets-Sheet 2 Q w k n fimbwm 1 .m K CA @FF 1 w? m am T d a? W g b,

June 6, 1933. w BRU KEL ET AL 1,913,188

SUPERVI SORY SYSTEM Filed June 9, 1930 4 Sheets-Sheet 3 Invermors: Waldemar Br-LJcKeI 9 RudolF Kberich,

Their Attorneg.

June 6, 1933. w. BRUCKEL ET AL SUPERVISORY SYSTEM Filed June 9, 1930 4 Sheets-Sheet 4 Patented June 6, 1933 UNITED STATES PATENT OFFICE WALDEMAB :ent'rcxnn, or 3mm, AND RUDOLF nonunion, or BERL IN-TEGEL, GER- MANY; AssIGNons To GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK Application filed .Tune" 1930, Serial; K014523345 and in Germanynecember 22, 1928.

Our invention relates to: supervisory systems, and more particularly to systems e111" ploying rotary selector switches in the different stations thereof. a

@ne of the objects of our inventionis to provide certain improvements in systems of the type indicated more particularly with reference to coordination of the code transmitting means and code responsive selecting means, the operation of the system over a single line conductor, the manner in which signals are repeated in the case of faulty operation of the equipment and the stormg of signals when two or more apparatus units operatesimultaneously or in close succession. In accordance with the invention a com plete transmitting and receiving system is provided in the dispatchers station and in the remote stations where the supervised ape paratus units are located. A control device, .or key, is provided in the dispatchers station corresponding to each apparatus unit supervised. Upon operation of any control device in the dispatchers station a pair of rotary selector switches in the dispatchers station are set into operation. These switches rotate until they each occupy positions corresponding to the operated control device. In this position a circuit is completed which energizes means for interrupting the driving circuits of the two switches and for ener-;

gizing a time responsive relay. Upon operation of the time responsive relay one of the:

switches is again set into operation and rotates over the remaining portion of its contacts to the normal position leaving the sec- 0nd switch in the position in which the time responsive means became energized. Means same number of impulses divided in groups by an intervening time interval so spaced in the series of impulses as to render the codes distmctive. w

A pair of slmilar selector switches is provided in the remote station together with a relay arrangement whereby in response to the first impulses received one of the selector switches is operated to a position corresponding to the number of impulses in the first group. During the interval between groups,

tlmmg means in the relay arrangement open impulses the two switches occupy complemote device corresponding to the operated f control deviceis selected and an impulse is transmitted back over the line conductor to the dispatche1"s station where means is operated through 9 the second selector switch in that station to restorethe operated control device and the second selector switch to the normal position and to interrupt operation of the first selector switch in the normal position.

Upon operation of the apparatus unit in the remote station the transmitting equipment in that station functions in the same manner to send impulses to the disptachers station over the line conductor. The receiving equipment responds to these impulses to operate appropriate signal devices and to;

1" ries of impulses are d1v1ded .mto complementary groups and whereby the selector switches in the remote station are operated to complementary positions dependent upon the number of impulses in each of the time spaced complementary groups.

Another object of the invention is to provide means whereby in case of failure of the return impulse the code will be continuously repeated until the return impulse is received or until a further control device is operated. Thus when a fault occurs resulting in failure of the return impulse, in accordance with the invention, the code will be continuously repeated until the return impulse is received,or until a further control device is operated. hen the latter occurs its corresponding code is automatically transmitted after which the equipment will again repeatedly transmit the former code. If the code corresponding to operation of the further control device also results in a fault such that no return impulse is received then the two codes will be in which Fig. '1 illustrates a transmitting 1 system, and Fig. 2 a receiving system for a dispatchers station and Figs. 3 and 4 illustrates respectively a transmitting system and a receiving system for a remote station.

Referring to Fig. 1 of the drawings, at 1 we have represented a plurality of manually operated switches each of which corresponds to one of the remote switches which are to be controlled and supervised. Each of these switches 1 has a pair of contacts 2 for initiating the operation of the supervisory system and an additional pair of contacts 3 for selecting the particular remote switch which is to be controlled. When any of the switches 1 is operated either to its left-hand position or to its right-hand position thereby to close or open a remote switch it is arranged to be mechanically latched in that position by a means of a latching mechanism 1 of any suit-' able construction. These latching mechanisms are each provided with an actuatmg winding 18 which when energized releases thearmature member of the switch 1 and tacts with a time delay. These, selector switches are so connected that, in response to operation of any switch 1, they actuate their armatures synchronously over a portion of their contacts after which an interruption occurs and selector 9 then returns to the initial position leaving selector 15 in the position in which the interruption occurred. In so doing, by means of an impulse relay 13, selector switch 9 supplies a series of impulses over the line conductor A to the remote station, the number ofimpulses transmitted corresponding to the number of contacts upon the selector switch 9. This series of impulses is interrupted, as stated, through actionof relay 17 for a definite interval after a predetermined number of impulses, as determined by the switch 1, has been transmitted after which interruption the series of impulses is completed by switch 9.

- In the remote station as illustrated in Fig. 4 selector switches and 56 are provided. Selector switch 55 is arranged to respond to the first group of the series of impulses, and selector switch 56 is arranged to respond to the second group of impulses whereby after the completion of the entire series of impulses these switches are upon contacts which are connected in circuit with the one of the relays 57, 58 which is to be operated to control the remote switch, not shown.

Impulses may be transmitted from the remote station to the dispatchers station for the purpose of indicating in the dispatchers station the automatic operation of any remote switch by means of a transmitting system shown in Fig. 3 which is identical. with the transmitting system shown in Fig. 1 with the principal exception that the equipment represented by the rectangle in Fig. 3 is provided instead of switches 1 shown in Fig. 1. In this transmitting equipment the starting and selecting circuits are completed through contacts on relays 26 and 27. A pair of these relays 26 and 27 is associated with each remote switch and the operation of any relay 27 causes a series of impulses to be transmitted over the line conductor A to the dispatchers station, the number of impulses transmitted corresponding to the selector switch 9 of the transmitting means shown in Fig. 3. The dispatchers oiiice is provided with a receiving system shown in Fig. 2 which is identical with that at the remote station with the exception that indicating relays, as shown in the rectangle in the lower left-hand corner of Fig. 2 are provided instead of relays 57 and 58 shown in Fig. 1.

The transmitter at the remote station is provided with additional relays 28 and 29 which are controlled through conductors g, h, and 2', 74 respectively by the remote receiver for purposes later to be indicated.

Having now indicated the general character of the system to be described, a further and more detailed understanding thereof may be had by reference to its operation.

switch in the position to which it is actuated.

Contacts 2 energize through an obvious circuit starting relay 5 in the dispatchers oflice and right-hand contacts 3 prepare a selecting circuit to determine the number of impulses in each group of the series which is to be transmitted thereby to select the desired remote switch.

Upon operation of relay 5 in the dis-M patchers station its upper contacts complete a circuit which extends from the negative side of the battery through the lower contacts of relays 51 and 52 of the receiver in the dispatchers station, contacts 53 of relay 53 of that receiver, conductor 0, upper contacts of relay 5, negative bus ('3, relay 7, and con tacts 8 on selector switch 9 to the positive side or "the battery. Upon operation of relay 7 a circuit is completed from the posi tive side of the battery through contacts of relay 7, winding of relay 10 and right-hand lowercontacts at a rate determined by a suitabletime delay means (not shown) which is associated with the relay whereby its operation to the lower position is delayed. This buzzer actionis utilized to control the operation of selectors 9 and 15.

As stated above when the relay 10 is in its upper position a circuit is completed through motor magnet 9 of switch9. Thus this motormagnet is successively energized and deenergized thereby stepping switch 9 over. its contacts synchronously with the buzzer action of relay 10. Upon each energization of motor magnet 9, contacts 14" associated therewith close thereby completing a circuit for the right-hand coil of impulsing relay 13 which, in turn, successively connects line A to the positive side or the battery. This circuit for relay 13 extends from the positive side of the battery throughco-ntacts 141 of motor magnet 9", rightghandcoil of relay 13, conductor 6, upper contacts of relay 5, conductor 0, contacts 53 of relay 53 in the dispatchers station, lower contacts of relays 52 and 51 to the negativeside of the battery. Contacts 14 also complete a circuit upon each successive energization of magnet 9 which extends through conductor 14, lower right-hand contacts of relay 11, wiper II which is in engagement with its first contact after the first energization of motor magnet 9, wiper 1 of selector switch 15 in its normal position and relay 16 to the negative side of the battery. Relay 16 then operates to complete an obvious circuit for motor magnet 15. of the selector switch 15.

This motor magnet 15. isthen energized and steps its armature on to its first ofi nor- 'mal contaetlthereby deenergizing relay 16.

Relay16 cannot then again be energized until selector switch 9 has been advanced to its sec ond contact by action of its motor magnet 9'. inresponse to successive operation of relay 10. WVhen this occurs relay 16 is again energized and the switch 15 is stepped to its second position. In this switches 9 and 15 operate synchronously until a contact is reached where the one of the selecting circuits which include contacts 3 of the particular switch 1, which has been operated, is completed. In the case assumed this circuit extends from negative, battery through the right-hand lower contacts of relay 13, contacts 14: of motor magnet 9, left-hand winding of relay 11, "wiper I on its eighth contact, right-hand contacts 3 of switchl, wiper II of switch 15 on its eighthcontact to the positive side of the battery. Since relay 13 must be in its lower position before this circuit can be completed, it will be apparent that this cannot be effected during the transmission of an impulse to the remote station.

When this circuit is completed the armature of relay 11 is operated to its left-hand position thereby completing a circuit from the negative bus 6 through left-hand contacts of relay 11 and slow closing relay 17. During the period of closing of relay 1? an interruption is produced in the transmission of impulses. The contacts of thisrelay are connected in parallel with the upper right-hand contacts of relay 11 so that when this relay is in its closed position the buzzer circuit of relay 1 0 is again completed. This circuit now extends through contacts 8 of switch 9, however, rather than 8 since switch 9 is in an oltnormal position. The circuit of motor; magnet 9 is also again completed through the contacts of relay 17. The selector switch Twill new actuate itself to its normal position in which position the movable contacts 8 open thereby interrupting the circuit of relay 10, and causing the switch to stop. It will be noticed that relay 7 was deenergized by contacts 8 when switch9 left its normal POSltlOZL- Selector 15, however,re

mains upon its eighth contact for the reason i 7 that the circuit of relay 16 is now open atthe right-hand lower contacts of relay 11. When contacts 8 close a circuit is again completed through the right-hand winding of relay 11 and the left-hand contacts of relay 13 to the negative bus whereby relay 11 is actuated back to the position shown in the drawings where it remains until the next operation.

The selector 9 would now again transmit a second series of impulses to the line A were it not for the fact, as will be indicated, that when the remote switch is operated a return impulse energizes magnet 18 thereby restoring switch 1 to the normal position and deenergizing the starting relay 5 which in turn deenergizes relay 7 and the negative bus 6.

At the remote station shown in Figs. 3 and 4 the positive impulses are received over conductor A through relay 50, conductor d, and right-hand lower contacts of relay 13 of the transmitter at the remote station. Thus relay 50 of neither receiving system'can respond when the transmitter in the same station is operating. Similarly since the bus 6 in each station is energized through relays 51, 52 and 53 thereat neither transmitter can operate when the receiver in the same station is operating. This relay 50 in Fig. 4 is operated in response to each impulse received from the dispatchers station and supplies the first group of impulses through a circuit which extends from the negative side of the battery through the left-hand contacts of relay 50, lower contacts of relay 54, motor magnet 55 of selector switch 55 to the positive side of the battery. Thus selector switch 55 steps its wiper over its bank of contacts through as many steps as there are impulses in the first group. Thus this switch will come to rest upon its eighth contact. The first closing of relay 50 causes relays 51, 52 and 53, all of which are cascade connected through obvious circuits, to operate their armatures to the upper position. When an interruption in the impulses, caused by the slow closing of relay 17 at the dispatchers station, occurs relay 51 at the remote station will actuate its armature to the lower position. A circuit will then be completed which extends from the negative side of the battery through the lower contacts of relay 51, middle contacts of relay 52 and actuating winding of relay 54 to the positive side of the battery. Relay 54 will then actuate its armature to its upper position and through its upper bridging member 54 will complete a holding circuit for itself which extends through bridging member 53 of relay 53 in its upper position. This transfers the circuit of the left-hand contacts of relay 50 from motor magnet 55 to motor magnet 56. Thus when the remaining group of'impulses are received motor magnet 56 will be actuated in response thereto thereby actuating the wiper to a contact depending upon the number of impulses included in the last group Since it is assumed that the entire series of impulses includes twelve impulses, for example.

, and the interruption occurred after the eighth impulse it will apparent that wiper 55 will now engage its eighth contact and wiper of switch 56 will engage its fourth contact.

When the second group of impulses is completed relay 51 and subsequently relay 52 at the remote station are deenergized. When relay 52 reaches its lower position a circuit is completed which extends from the negative side of the battery through the lower contacts of relays 51 and 52, bridging meni- 3 right-hand winding. Relay 13 at the remote station then actuates its armature and supplies positive potential to the conductor A. This potential comprises the return signal impulse which occurs only when switches 55 and 56 have properly operated. This potential, however, will not cause operation of relay 50 of the remote receiver for the reason that the circuit of relay 50 is completed through conductor (Z and the right-hand lower contacts of the relay 13 of the remote transmitter which are now open.

After a further time delay relay 53 at the remote station operates its armature to the lower position thereby closing circuits which extend from the negative side of the battery through the lower contacts of relays 51 and 52, bridging member'53 of relay 53 in its lower position, contacts 56 which are now closed due to the fact that the wiper of switch 56 is not in its normal position, contacts 56 of the motor magnet 56 and winding thereof to the positive side of the battery. This circuit constitutes a buzzer circuit for the motor magnet 56 which actuates the switch 56 to its initial position, in which position the contacts 56 are opened and the operation ceases. A similar circuit is completed through the bridging member 53 of relay and its lower contacts for the motor magnet 55- which likewise actuates its armature to the normal position.

It hassbeen seen that at the same time that relay 57 at the remote station was energized positive potentialwas supplied by the transmitter at the remote station to the conductor A. Relay 50 of the receiver at the dispatchers station shown in Fig. 2 responds to this positive potential and causes the operation of relays 50, 51, 52 and 53 thereat to their upper position thereby energizing motor magnet 55 at the dispatchers station. When the switches 55 and 56 at the remote station return to their initial position, however, the circuit of the left-hand winding of relay 13 dispatchers station are returned in succes sion to the positionshown in the drawings thereby deencrgizhig motor magnet 55 at the dispatchers station Switch 55 in the dispatchefls station now occupies its first contact position. 1 1

A circuit is then completed in the dispatchers oliice from the negative side of the battery through the lower contacts of relays 51 and 52, bridging member 53 of relay 53 in. its upper position, wiper of switch .55 on itsfirst contact, conductor wiper III of selector-switch 15 at the dispatchers station on its-eighth contact, winding 18 oflatching member 1', contacts 18 otselector switch 9 to the positive side ofthe battery. -Winding 18 then releases the latching member 1 and thereby restores .the switch 1 to the position shown in the drawings. This in turn deenergizes the starting relay 5 which operates to its lower position after a time delay.

In its lower position relay 5 completes a circuit which extends from negative battery through the lower contacts thereof,1 contacts 15, contacts 15 motor magnet 15 tothe positive side of the battery. This constitutes a buzzer circuit for motor magnet 15 which in turn actuates its wipers to the initial position in which position contacts 15 arejopen-H .blVGfiOIlClllCiLOI 6 obvious circuits for visual V ed thereby interrupting the operation of; the

switch. After a time delay relay 53 at the dispatchers station returns to its lower posi tion thereby completing the buzzer circuit for the motor magnet 55 which in turn actuates the corresponding selector switch to its nitial position. Thus the entire system is nowreturned to its initial position. i h

Let us assume that when the selector switch 9 in the dispatchers office is returned to its 1 initial position the above described final impulse caused by relay 13 at the remotestation does not occur due, for example, to faulty operation of one of the switches 55 or 56 at the remote station. It will be seen that when the contact of switch 9 returns to its initial position relay 7 isenergized through contacts 8 and completes the buzzer circuit for relay 10. Through operation of this relay as described above, theseries of impulses will be repeated to the remote station. The

selector switch 15, however, willremain upon the contact to which it was actuated, viz: in

the case above assumed, contact 8 since the circuit of the control relay 16 is not again completed before the relay 11 1s reenerglzed to open its contacts in the energ1z1ng circu t for the relay 16.

When switch 9 reaches its eighth contact the left-hand winding of relay 11 will be energized thereby, as before, energizing re lay 17 and producing the interruption between the two series of impulses.

the remote station.

, By making relay 7 sulficiently slow to 0p crate, or otherwise, producing sufiicient time interval after the first series has been sent a time interval, equal to the time required for two complete series of impulses when no remote operation is had closes its contacts thereby completing a circuit which extends from the positive side of the battery through contacts 8 which are closed when this switch is in its normal position, left-hand contacts of relay 19 and winding ofrelaylb tothe negative side of the battery. Relay 16 closes thereby energizing motor magnet 15 and stepping selector switch 15 an additional step. When this occurs relay 19 is deenergized through a momentary interruption of contacts15 after which it again becomes energized. In its upper position it also completes a circuit which extends from the negative side of the battery through relay 20, armatureof relay 19, contacts 8 on selector switch and audible indicating devices 21 and 22 which inform the operator that faulty operation of the equipment has taken place.

Relay 20 may be employedto operate a drop as indicated in the drawings thereby to furnish a permanent indication that trouble has occurred. 1

Since switch 15 is no longer on a contact corres nding to the operated signal lever 1 the leit-hand winding of relay 11 will not be operated on the following rotation of switch 9 but will remain in its right-hand position. Thus if no other switch has been operated the switch 15 will then be actuated along with switch 9 to the normal position. The system is then in readiness to respond to another signal operation. If, however, the switches 1 corresponding to subsequent contacts on switch 15 have been operated, the switches 9 and 15 instead of being restored to their normal positions in the manner above described will stop when the switch 15 engages the first of these contacts, and after a time delay the switch 9 will return to its. normal position. In this manner the code corresponding to the contact with which the switch 15 remains in engagement is transmitted to the switches 9 and 15 at Thus, when a faulty operation occurs the equipment not only transmits the code during which the faulty operation occurred but also transmits any further codes corresponding to other operated control switches. That is, let us assume that these control devices 1 are operated substantially simultaneously or one following the other in succession without intervening interval sui'iicient to permit the equipment to return to normal after any operation.

Normally the equipment will proceed to transmit the respective codes in succession.

I if we assume that no return impulse occurs after the first code is transmitted the equipment will repeat this code once and then proceed to send the codes corresponding to each of the other operated units in success on, after which it will continuously repeat the first code. If we assume that no return impulse is received corresponding to two or a greater number of operated devices 1, it will be seen that the equipment will re-transniit the codes corresponding to each of these To indicate the manner in which the re-- mote switches in Fig. 3 are caused, upon operation thereof, to actuate the remote transmitter thereby to operate signals in the dispatchers station the equipment indicated in the rectangle at the lower left-hand corner of Figs. 2 and 3 is provided. The equipment hown in the rectangle of Fig. 3 includes the relays 26 and 27 which are associated with each remote switch at the remote station and that in the rectangle of Fig. 2 includes the relays 59, 60 and 60 which are located in the dispatchers station and which correspond to the remote switches.

If we assume that a remote switch (not shown) is operated from one position to the other a contacting device 23 is rotated "hrough one-half of a revolution and thereby completes a conductive connection between contacts 23 and 23. A circuit will then be completed which extends from negative battery through contacts 23 and 23 of conacting devices 23, upper contacts and armature of relay 26 in the position shown and the left-hand winding of relay 27 to the positive terminal of the battery. Relay 27 will then be actuated to the left thereby completng starting circuit which extends from the negative side of the battery through starting relay 5 of the remote transmitter, lower left-hand contacts and armature of relay 26, upper contacts and armature of relay 27 in its left-hand position to the positive side of the battery. Likewise a selecting circuit will be completed which extends from the fifth contact on bank I of switch 9 through the middle contacts and armature of relay 26 in the position shown, lower contacts and armature of relay 27 in its left-hand position, conductor 63, and fifth contact of bank II of switch 15. Thus the starting circuit and the selecting circuit is completed in the same way as is done by means of switches 1 at the dispatchers station.

When a corresponding signal is received at the dispatchers station the selector switch of the dispatchers receiver shown in Fig. 2 will be operated to its fifth contact and selector 56 will be operated to its seventh contact, thereby operating the left-hand coil of relay 59 and relay 60 in parallel. By means of its lower contact relay 60 energizes an obvious circuit for audible signaling device 61. Relay 59 similarly closes an obvious circuit for the visual indicating devices 62 which may comprise a lamp. When the return signal impulse is received at the remote station a circuit will be completed for the right-hand coil of relay 26 which in turn operates the armature to the dotted line position thereby interrupting both the starting circuitand the selecting circuit in a manner equivalent to the return of switch 1 to its normal position.

In case the switch 27 has then been actuated back to its initial position a circuit for the starting relay will again be completed through lower right-hand contacts and armature of relay 26, and the upper right-hand contacts and armature of relay 27. Similarly a selecting circuit will be completed through the middle right-hand contacts of relay 26 and lower right-hand contacts of relay 27. These circuits in turn will cause the apparatus to operate through a complete cycle sending its signal to the remote station and finally energizing the left-hand coil. of relay 27 and returning the armature to the position shown in the drawings.

It will be apparent that if a number of remote switches are operated simultaneously the selector switches 9 and 15 will operate to the contacts corresponding to the first of these switches after which its signal will be sent to the dispatchers station. The supervisory system will then proceed to send signals corresponding to each of these switches in sequence and repeating the signals following which no return signals are received all in the manner above explained.

Relays 28 and 29 are arranged to be operated by the receiver at the remote station in the same way that relays 57 and 58 are operated, and are used for the purpose of checking the position of the remote switches. Thus, for example, if the operator desires to check the position of the remote switches he will first operate relay 28. This relay inc Q actuated. These switches will then cause a signal to be sent to the dispatchers station indicating the position which they occupy. The operator will then operate relay 29 which in turn through conductors 60, 61 and 62 will Q energize the right-hand coils of all of the i relays 26. This in turn will cause all of the armatures which are not already in the righthand position to be actuated to the right and corresponding signals to be sent to the dispatchei"s station g It will be noticed that the operating windings of the relays and 60 are respectivelyconnected in parallel with the left-hand winding and the right-hand winding of the {relay 59. When the positions of remote switches are being checked as by relays 28 and 29, if no change has occurred, only the drops will be effected. If a change has occurred both a lamp and a drop will be en- 5 ergized thereby informing the operator that a change has occurred which has not previously been reported. The drops will always be operated in response to each checking oporation and failure thereof indicates a faulty .g'iperation of the equipment.

While we have shown a particular embodi ment of our invention it will be understood by those skilled in the art that many changes and modifications, both in the circuit ar- 5rangement and inthe instrumentalities cum ployed, may be made without departing from our invention and we therefore aim in the appended claimsto cover allsuch changes and modifications as fall within the true ispirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States 1s: i

1. In combination, a of stepby-step '"otary selector switches, each of said selector switches hav ng a normal position and a plurality of other positions, a plurality of control devices, each of said devices corre= spending to a certain position of said. switch- 0 means responsive to operation of of said devices tooperate said sw tches in synchronism to a position corresponding to the operated device, means dependent upon said switches occupying said corresponding posi- 5 ons for interrupting the operatiouof both of said sw tches for a predetermined time interval and for thereafter causing one of said switches to operate to said normal positio wl'iile the other switch remains in said 0 rresponding position, means for transmit ting an impulse n response to each step-o said one switch. selecting means at a remote point responsive to said impulses when the impulses received at said remote point cor- 5 respond to the impulses transmltted, control turn said other selector switch to the normal pos1tion when the impulses received at said remote point correspond to the impulses transmitted.

2. In combination, a pair of step-by-step rotary selector switches, each of said selector switches having a normal position and a plus rality of other positions, a plurality of control devices each of said devices corresponding to a certain position of said switches, means responsive to operation of any of said devices to operate said switches in synchronism to a position corresponding to the operated device, means dependent upon said switches occupying ,sad corresponding positions for interrupting the operation of both of said switches for a predetermined time interval and for thereafter causing one of said switches to operate to said normal position while the other switch rema ns in said ated with each control device and means responsive to said impulse and the position of said other selector switch to effect the operation of the control means associated with the operated control device and torestore said other switch to the normal. posit on.

3. Incombination, a pair of step-hy-step selector switches, each of said selector switches having a normal position and a plurality of other positions, a drive circuit for each. switch, a plural ty of control. devices, each of said control devices corresponding to a position of said switches, control means associated with each control device, means responsive to operation of any of said control devices to complete the drive circuit of one of said sw tches. means for operating the other switch synchronously with said one switch until a position corresponding to the operated control device is reached, means responsive to said switches occupying said position corresponding to the operated control dev ce for interrupting said drive circuit and for interrupting operation of said last means, time-controlled means for again completing said drive circuit, impulse sending means respons1ve to operation of said one switch, impulse responsive means ata remote point, means responsive to operation of said impulse responsive means for interrupting operation of said first switch in the normal position when the impulses received at said remote point correspond to the impulses transmitted and means controlled by 331d impulse responsive means and the position of said second switch for eiiiecting the operation of the control means associated with .he operated control device and for returning said second switch to the normal position when the impulses received at said remote point correspond to the impulses transmitted.

i. In combination, a pair of step-by-step selector switches, each of said switches having a normal position and a plurality of other positions, a plurality of control devices, means responsive to operation of each of said lOIlillOl devices for operating said switches to a position corresponding to the operated control device, means responsive to operation of both of said switches to said position for interrupting the operation of one oi said witches, code sending means controlled by said other switch, code responsive means at a remote point, selecting means at said remote point operated by said code responsive means when the code received by said code esponsive means corresponds to the code transmitted by said other switch means responsive to operation of said code responsive means when the code received by said code responsive means corresponns to the code ransmitted by said other switch and operable through said one selector switch to restore the operated control device to the normal condition and to prevent operation of said other switch in the normal position.

5. In combination, a pair of step-by-step selector switches, each of said switches having a normal position and'a plurality of other positions, a plurality of control devices, means responsive to operation of any "ontrol device for synchronously operating said switches through said positions, a plurality of circuits including corresponding contacts on each of said switches and the corresponding control device, means includlig said circuits for interrupting the operation of said switches in a position corresponding to the operated control device and after a predetermined interval causing one of said switches to again operate, means for "iransmitting a code determined in accordance with the position in which the operation of said switches was interrupted, code responsive means, selecting means at said re mote point operated by said code responsive deans when. the code received by said code responsive means corresponds to the code transmitted and means controlled by the code responsive means through said other switch in said position to prevent operation.

if said first switch in the normal position when the codereceived by said code responsive means corresponds to the transmitted code.

6. In combination, a pair of step-by-step selector switches, each of said switches having a normal position and a plurality of other positions, a plurality of control devices, means responsive to operation of any control device for synchronously operating said switches through said positions, a plurality of circuits including corresponding contacts on each of said switches and the corresponding control device, means including said circuits for interrupting the opera- .tion of said switches in a position corresponding to the operated control device and after a predetermined interval causing one of said switches to again operate, means for transmitting a code determined in accordance with the position in which the operation of said switches was interrupted, code responsive selecting means, and means operable upon failure of said code responsive means to effect a selection corresponding to the operated unit to actuate said other selector switch to another position thereby to interrupt said circuit through said operated control device whereby said switches again operate synchronously through said positions.

7. In combination, a pair of step-by-step selector switches, each of said switches having a normal position and a plurality of other positions, a plurality of control devices, means responsive to operation of any control device for synchronously operating said switches through said positions, a plurality of circuits including corresponding contacts on each of said switches and the corresponding control device, means including said circuits for interrupting the operation of said switches in a position corresponding. to the operated control device and after a predetermined interval causing one of said switches to again operate, means for transmitting a code determined in accordance with the position in which the operation of said switches is interrupted, code responsive means, means controlled by the code responsive means through said other switch in said position to prevent operation of said first switch in the normal position, and means operable upon failure of said code responsive means to aiilect a selection corresponding to the operated control device to actuate said other selector switch to another position thereby to interrupt said circuit through said operated control device whereby saidswitches again operate synchronously through said positions.

8. In combination, a pair of step-by-stcp selector switches, each of said switches having a normal position and a plurality of other positions, a plurality of control devices, means responsive to operation of any control device for synchronously operating said switches through said positions, a plurality of circuits including corresponding contacts on each of said switches and the corresponding control device, means including said circuits for interrupting the operation of said switches in a position corresponding to the operated control device and after a predetermined interval causing one of said switches toagain operate, means for transmitting a code determined in accordance with the position in which the operation of said switches was interrupted, code responsive selectlng means, means for preventmg operation of said first switch 1n the normal position, in response to operation of saidcode responsive means to effect a selection corresponding to the operated control device, whereby upon failure of said code responsive means to efiect said selection said one switch continues to operate and said code is retransmitted, and meansoperable after said code has been retransmitted to operate said other switch to a different position thereby to interrupt said circuit 1 through said operated control device wherei 1 by said switches again operate synchronous- 1y through said positions.

In witness whereof, we have hereunto set our hands this 21st day of May 1930.

WALDEMAR BRUCKEL. RUDOLF KOBEBIOH. 

